This invention relates to a burner apparatus comprising an inner tube defining a second channel and an outer tube defining a first channel surrounding the inner tube, air supplying means (an example of oxygen-containing gas supplying means) for supplying air (an example of oxygen-containing gas) to the first channel and the second channel, and gas supplying means for supplying fuel gas to the first channel and the second channel, either the first channel or the second channel being used as a main combustion channel and the other being used as a pilot combustion channel, the main combustion channel and the pilot combustion channel receiving the supply of fuel gas for combusting it. The invention relates also to a gas turbine engine including said burner apparatus and a co-generation system including the gas turbine engine. The invention further relates to a fluid distributor for use in such gas turbine engine including the burner apparatus, the co-generation system including the gas turbine engine, the burner apparatus, the distributor being disposed across three channels including first and second channels through which a first fluid such as air is caused to flow and a gas channel (an example of fluid channel) through which a second fluid such as fuel gas is caused to flow, so that the distributor distributes the fuel gas inside the fluid channel between the first channel and the second channel.
The burner apparatus described above is used as a burner apparatus for a gas turbine engine used in a co-generation system or a burner apparatus used for an incinerator. With this burner apparatus, it is necessary not only to adjust the flow amounts of the fuel gas to be fed to the main combustion channel and the pilot combustion channel, in accordance with increase/decrease in the combustion load for assuring good combustion with maintaining appropriate equivalent ratio for the main combustion channel and the pilot combustion channel, but also to adjust the flow amounts of the air to be fed to the main combustion channel and the pilot combustion channel.
Conventionally, in order to make the adjustment of the flow amounts of the fuel gas to the main combustion channel and the pilot combustion channel, a flow-amount adjusting valve was provided in a fuel gas supply line to the main combustion channel and in a further fuel gas supply line to the pilot combustion channel, respectively, so as to make the adjustment of the flow amounts of the fuel gas to the main combustion channel and to the pilot combustion channel, independently of each other.
However, according to the prior art described above, as the adjustment of the supply amount of fuel gas to the first channel and that to the second channel in accordance with the combustion load are effected independently of each other, the adjustment operation was troublesome.
Further, in the case of the burner apparatus of the above type which effects pilot combustion and main combustion, the supply amounts of fuel gas respectively to the main combustion channel and to the pilot combustion channel are reduced in association with decrease in the combustion load relative to a rated combustion load. In association with such decrease in the supply amount, it is necessary to increase the supply amount to the pilot combustion channel to maintain stable pilot combustion.
Moreover, with such burner apparatus, it is especially needed to mix fuel gas and air in a reliable manner inside the first channel in which the main combustion is effected. For, if they are not mixed well, there occurs unevenness in the equivalent ratio in the fuel-air mixture containing the fuel gas and the air in a mixed state, so that in a region of a higher equivalent ratio high-temperature combustion will occur, resulting in increase in NOx generation amount.
According to the conventional burner apparatus, as shown in FIG. 44, a supply line provided within the combustion channel for receiving fuel gas supply defines a plurality of supply openings arranged in dispersion for discharging the fuel gas through the plural openings to the combustion channel. In this case, the plural supply openings are opened on the downstream side in the direction of air flow in the combustion channel, so as to discharge the fuel gas in the same direction as the air. With this construction, by dispersing the supply of fuel gas to the combustion channel, the apparatus was designed to improve the mixing degree between the air and the fuel gas G.
With such conventional burner apparatus, in order to achieve uniformity in the supply of fuel gas to the combustion channel by providing a plurality of supply openings for one supply line, it is desirable for the supply openings to be provided as many as possible. However, as the total amount of fuel gas to be supplied to the combustion channel is determined in advance, as the number of the supply openings is increased, it becomes necessary to reduce the opening area of each supply opening.
As a result, there occurs increased pressure loss at the supply openings. Then, in order to discharge a predetermined amount of the fuel gas, it becomes necessary to supply the fuel gas with an increased pressure into the supply line, thus requiring disadvantageous physical and capacity enlargement of the gas supplying means for the burner apparatus.
Incidentally, the equivalent ratio represents an amount indicative of concentration aspect of the fuel-air mixture of the fuel and the combustion air and this is defined herein as follows.
xe2x80x83equivalent ratio=(fuel concentration/air concentration)/(fuel concentration/air concentration)St
Each concentration is represented in the mole value, and (fuel concentration/air concentration) St is a theoretical fuel-air ratio. This theoretical fuel-air ratio is the concentration ratio between an amount of fuel and air needed for complete oxidation of that amount of fuel.
Therefore, an object of the present invention is to provide a fluid distributor which allows easy adjustment of the supply amounts of fuel gas to the main combustion channel and the pilot combustion channel depending e.g. on the combustion load and which also allows increase in the distribution ratio of the supply amount to the pilot combustion channel in association with decrease in the supply amount, as well as a preferred burner apparatus using the distributor, a gas turbine engine including the burner apparatus and a co-generation system including the gas turbine engine.
A further object of the present invention is to provide a burner apparatus which achieves reduced pressure loss occurring when the fuel gas is supplied to the combustion channel and which also achieves superior mixing of the fuel gas and the air.
In order to accomplish the above-noted objects, the burner apparatus according to the present invention is characterized in that said gas supplying means includes a plurality of fluid distributors arranged in dispersion in a peripheral direction of the main combustion channel and the pilot combustion channel, each fluid distributor including a first supply opening for supplying the fuel gas into the main combustion channel, a supply line for supplying the fuel gas present inside the gas channel to the first supply opening, and distributing means incorporated in the supply line for distributing the fuel gas into the pilot combustion channel so that the distribution ratio of the fuel gas to be supplied to the first supply opening is increased in response to increase in a total supply amount of the fuel gas from the gas channel and conversely the distribution ratio of the fuel gas to be supplied to the first supply opening is decreased in response to decrease in the total supply amount.
Further, the burner apparatus according to the present invention, in addition to the burner apparatus construction described above, is further characterized in that the first channel is used as the main combustion channel and the second channel is used as the pilot combustion channel.
That is to say, the first channel used as the main combustion channel receives air from the air supplying means and receives also the fuel gas present inside the gas channel via the gas supplying means, so that the fuel-air mixture of the air and the fuel gas is produced therein and this fuel-air mixture is ignited to provide main combustion of the fuel-air mixture. On the other hand, the second channel used as the pilot combustion channel receives the air from the air supplying means and receives also the fuel gas present inside the gas channel via the gas supplying means, so that the fuel-air mixture of the air and the fuel gas is produced therein and this fuel-air mixture is ignited to provide pilot combustion of the fuel-air mixture.
And, the gas supplying means comprises the fuel distributors adapted for supplying the fuel gas to the main combustion channel and the pilot combustion channel and adapted also for distributing the fuel gas present inside the gas channel between the main combustion channel and the pilot combustion channel. That is, as the fluid distributor includes the distributing means incorporated within the supply line for supplying the fuel gas inside the gas channel to the main combustion channel via the first supply opening, the distributor distributes the fuel gas to the main combustion channel and also to the pilot combustion channel. Further, the distributor is constructed so that the distribution ratio of the fuel gas to be supplied to the first supply opening is increased in response to increase in a total supply amount of the fuel gas from the gas channel and conversely the distribution ratio of the fuel gas to be supplied to the first supply opening is decreased in response to decrease in the total supply amount.
Therefore, it is not necessary to adjust the supply amount of the fuel gas to the main combustion channel and the supply amount of the fuel gas to the pilot combustion channel respectively and independently of each other. Rather, adjustment of the distribution ratio of the fuel gas between the main combustion channel and the pilot combustion channel in accordance e.g. with variation in the combustion load can be done simply by adjustment of the total supply amount of the fuel gas to the fuel gas channel. Moreover, with the burner apparatus according to the present invention, in association with decrease in the total supply amount of the fuel gas at the time of low combustion load, the supply amount of the fuel gas to the pilot combustion channel is increased to provide stable pilot combustion; whereas, in association with increase in the total supply amount of the fuel gas at the time of rated combustion load, the supply amount of fuel gas to the main combustion channel is increased, thereby to uniformly supply the fuel gas to the main combustion channel and the pilot combustion channel so as to realize low NOx combustion with lean fuel-air mixture. As a result, with such simple construction, it is possible to achieve higher efficiency over a wide combustion load range.
In addition, since a plurality of such fluid distributors for supplying the fuel gas to the main combustion channel and the pilot combustion channel are distributed along the peripheral direction of the main combustion channel and the pilot combustion channel, the fuel gas may be supplied in distribution in the peripheral direction into the main combustion channel and the pilot combustion channel, thereby to provide good mixing between the fuel gas and air inside the main combustion channel and the pilot combustion channel. As a result, uniformity of the fuel-air mixture can be obtained.
Also, with the burner apparatus of the present invention, in the outer first channel and the inner second channel, either combustion channel may be used as the main combustion channel. However, by using the outer first channel as the main combustion channel and the inner second channel as the pilot combustion channel, it becomes possible to increase the fuel gas in the inner pilot combustion channel at the time of low combustion load for increasing the distribution ratio of the fuel gas for the pilot combustion channel, thereby to provide stable pilot combustion in the pilot combustion channel.
Moreover, in this case of using the outer first channel as the main combustion channel and the inner second channel as the pilot combustion channel, it is possible to insert a gas tube defining the gas channel into the inner tube defining the second channel as the pilot combustion channel, whereby the gas channel, the pilot combustion channel and the main combustion channel are formed in this order from the inner side to the outer side, and the supply line for supplying the fuel gas from the gas channel to the first supply opening is formed to transverse the pilot combustion channel. Hence, the distributing means can be formed easily at this portion where the supply line(s) transverses the pilot combustion channel.
On the other hand, if the outer first channel is used as the pilot combustion channel and the inner second channel is used as the main combustion channel, it becomes possible to reduce the length of an ignition plug which is to be inserted into the pilot combustion channel from the outside.
Incidentally, as each of the inner tube and outer tube described above, a tube having a circular cross section may be employed of course. However, an angular tube having a polygonal cross section can be employed instead for example.
Further, the burner apparatus of the present invention, in addition to the burner apparatus construction described above, is further characterized in that in the distributing means includes, in the supply line, a second supply opening for discharging the fuel gas into the pilot combustion channel in a direction normal to the flowing direction of the air inside the pilot combustion channel and a communication line for receiving the fuel gas discharged from the second supply opening and guiding the gas into the first supply opening, and at a position opposed to the second supply opening and spaced apart by a predetermined distance in the discharging direction of the second supply opening, there is provided a receiving opening of the communication line as to be open toward the second supply opening.
That is, with the burner apparatus of the present invention, the gas tube is provided adjacent the pilot combustion channel and its gas channel includes the second supply opening for discharging the fuel gas to the pilot combustion channel and the receiving opening is provided at the portion of the inner tube opposed to the second supply opening via the pilot combustion channel and to which the discharge of the fuel gas is oriented.
Namely, the fuel gas supplied into the gas channel is discharged through the second supply opening toward the receiving opening to the pilot combustion channel.
And, in a second gas supply area where the fuel gas discharged in the pilot combustion channel is present, a portion of the fuel gas transversing the pilot combustion channel will be carried away by the air current of the pilot combustion channel to the downstream side of this pilot combustion channel while the rest of the fuel gas will be carried across the air current of the pilot combustion channel to reach the first supply opening via the receiving opening and will eventually be supplied to the main combustion channel.
More particularly, of the fuel gas discharged from the second supply opening into the pilot combustion channel, its portion introduced into the communication line from the receiving opening is guided via the communication line to the first supply opening to be supplied into the main combustion channel, whereas the remaining portion of the fuel gas not introduced into the receiving opening is supplied to the pilot combustion channel. And, the greater the supply amount and the higher the speed of the fuel gas discharged from the second supply opening, the higher the ratio of the portion of the fuel gas discharged from the second supply opening to enter the receiving opening. As a result, the greater the supply amount of the fuel gas, the greater the distribution ratio of the fuel gas for the first supply opening, that is, for the side of the main combustion channel. Conversely, the smaller the supply amount of the fuel gas, the smaller the distribution ratio of the fuel gas for the side of the main combustion channel.
Therefore, in the burner apparatus, by simply providing the second supply opening and the communication line having the receiving opening, with such simple construction, the distributing means of the fluid distributor may be provided.
Further, the amount of air flowing in the pilot combustion channel is normally contained within a predetermined range, so that e.g. the positional relationship between the second supply opening and the receiving opening is fixedly established. Hence, by increasing the supply amount of the fuel gas from the second supply opening, the ratio between the amount of the fuel flowing to the downstream side of the pilot combustion channel and the amount of the fuel to be supplied to the pilot combustion channel may be reversibly varied in association with increase/decrease in the fuel supply amount.
Further, the burner apparatus of the present invention, in addition to the burner apparatus construction described above, is characterized further in that said fluid distributor includes a plurality of said first supply openings distributed in the main combustion channel in a direction away from the pilot combustion channel.
That is, by using the fluid distributors mounted inside the main combustion channel with the plurality of first supply openings distributed in the direction away from the pilot combustion channel, i.e. in the radial direction of the first and second channels, even greater uniformity of the fuel-air mixture can be obtained, thereby to reduce the equivalent ratio for NOx generation reduction by lean combustion and also for stabilization of the lean combustion.
Further, the burner apparatus of the present invention, in addition to the burner apparatus construction described above, is characterized in further that the supply line is provided in correspondence to each of the plurality of first supply openings.
That is to say, as the supply line is provided in correspondence to each of the plurality of first supply openings, in comparison with e.g. a case in which the fuel gas is supplied to the plurality of first supply openings via one supply line, it is possible to reduce the pressure loss which would occur for supplying the fuel gas uniformly from the plurality of first supply openings.
Therefore, it becomes possible to further improve the uniformity of the mixture between the air and the fuel gas inside the main combustion channel while reducing the pressure loss, so that the pressure loss associated with the fuel gas supply may be reduced while maintaining the low NOx generation performance.
Further, the burner apparatus of the present invention, in addition to the burner apparatus construction described above, is characterized in further that the fluid distributor is constructed such that the supply lines corresponding to the plurality of first supply openings are formed in a plate-like member disposed within the main combustion channel with its plate surface oriented along the air flow direction.
That is to say, the plurality of supply lines are formed in the plate-like member disposed within the main combustion channel in alignment with the air flow direction, so that the plate-like member forming the supply line is disposed along the air flow direction. Hence, in spite of the provision of the plurality of supply lines, this hardly interferes with the air flow.
Moreover, as the plurality of supply lines are formed together as a group within the plate-like member, the handling such as assembly is easy.
Therefore, it is possible to supply the fuel gas uniformly relative to the air while maintaining good air flow in the main combustion channel. Further, in spite of the provision of the plurality of supply lines, the handling such as maintenance, assembly or the like is improved.
Further, the burner apparatus of the present invention, in addition to the burner apparatus construction described above, is characterized in further that the plate-like members of the plurality of fluid distributors are disposed with each plate surface thereof oriented along the spiral direction of the main combustion channel so as to act as a fin of a swirler for providing a swirling force to the supplied air.
In such burner apparatus, as the swirler provides the swirling force to the air to be supplied to the main combustion channel to enhance the mixing degree between the air and the fuel gas, the lean combustion can take place effectively. In this regard, attention was directed to the fact that the fluid distributor for distributing the fuel gas inside the gas channel to the main combustion channel and the pilot combustion channel includes the plate-like member forming the first supply openings and the supply lines. Then, by disposing this plate-like member in alignment with the spiral direction of the main combustion channel, this plate-like member can constitute a swirler fin. Hence, the fluid distributor and the swirler can share the same member.
Accordingly, while achieving the improved uniformity in the mixing performance, it has become possible to achieve simplification and cost reduction of the construction.
Further, the burner apparatus of the present invention, in addition to the burner apparatus construction described above, is characterized in further that at a portion of the main combustion channel more downstream than the first supply openings in the air flow direction, there is provided a swirler for providing a swirling force to the fuel-air mixture of the air and the fuel gas in the spiral direction of the main combustion channel.
In the burner apparatus of the present invention, at the portion of the main combustion channel on the downstream of the fluid distributors, the swirler for improving flame stability of the main combustion may be provided for providing a swirling force to the fuel-air mixture of the air and the fuel gas. So that, the orientation of the first supply opening may be simple. Moreover, without disturbing the air flow at the first supply opening, the fuel-air mixture may be swirled for improving the flame stability of the main combustion.
Accordingly, it has become possible to further improve the lean combustion performance.
Further, the burner apparatus of the present invention is characterized in further that the first supply opening is disposed, in the main combustion channel, with an orientation for discharging the fuel gas toward more upstream side of the flow direction of the oxygen-containing gas than the direction normal to the flow direction of the oxygen-containing gas.
That is, by disposing the first supply opening with such orientation for discharging the fuel gas toward more upstream side of the flow direction of the air than the direction normal to the air flow direction, the fuel gas is to be discharged against the flow of the air in the main combustion channel. As a result, the fuel gas and the air will collide against each other for providing natural stirring and mixing of the fuel gas in the air and will be diffused in both the radial and peripheral directions of the main combustion channel.
In this way, with the burner apparatus of the present invention, for achieving the uniform discharge of the fuel, it is not needed to provide a great number of first supply openings of a small diameter. Instead, this is possible by increasing the aperture diameter of the first supply opening. Therefore, no significant pressure loss occurs in association with the supply of the fuel, and the mixing degree between the fuel gas and the air may be enhanced by utilizing the air flow.
Moreover, in order to allow the fuel gas to be discharged from the first supply opening, this is possible by providing the fuel gas with a pressure overwhelming the pressure of the circulating air. In this regard, this air pressure is of such magnitude as hardly affects the discharging of the fuel gas. Accordingly, it is not necessary to enlarge the gas supplying means for supplying the fuel gas. Instead, the fuel gas may be mixed reliably with a simple device. Consequently, it becomes possible to provide a burner apparatus which achieves further reduction in NOx generation amount.
And, in combination with the fluid distributor used as the gas supplying means in the present invention, in the distributing means, in supplying the fuel gas through the route from the second supply opening, the pilot combustion channel, the receiving opening, the first supply opening to the main combustion channel, as the first supply opening is configured, as described above, to discharge the fuel gas toward the upstream side in the air flow direction thereby to reduce the pressure loss through the first supply opening, the fuel gas discharged from the second supply opening into the pilot combustion channel may be received efficiently into the receiving opening communicated with the first supply opening with the reduced pressure loss. Thus, the mechanism can be realized with a relatively simple construction.
Further, the burner apparatus of the present invention, in addition to the burner apparatus construction described above, is characterized in further that the first supply opening is disposed, in the main combustion channel, with an orientation for discharging the fuel gas in a direction opposing to the air flow direction.
That is to say, in the case of this construction in which the first supply opening is configured to discharge the fuel gas in the direction opposing to the flow direction of the air, the relative speed between the fuel gas and the air discharged is maximized, so that the mixing degree of the fuel-air mixture in the main combustion channel can be maximized as well.
Further, the burner apparatus of the present invention is characterized in further that the main combustion channel includes a mixing promoting member against which the fuel gas discharged from the first supply opening into the main combustion channel is collided to be diffused in the main combustion channel or the pilot combustion channel includes a mixing promoting member against which the fuel gas discharged from the second supply opening for supplying the fuel gas into the pilot combustion channel is collided to be diffused in the pilot combustion channel.
Further, in the case of the apparatus being combined with the fluid distributor as the gas supplying means in the present invention, the burner apparatus of the present invention is characterized in that the apparatus includes a mixing promoting member against which the fuel gas discharged from the first supply opening into the main combustion channel is collided to be diffused in the main combustion channel.
That is to say, by providing such mixing promoting member, it is possible to collide the fuel gas discharged from the supply opening against the mixing promoting member to be diffused thereby, so that the fuel-air mixture may be rendered further uniform in the main combustion channel or in the pilot combustion channel.
Moreover, the burner apparatus of the present invention, in addition to the burner apparatus construction described above, is characterized in further that the mixing promoting member comprises a ring-like member disposed along the peripheral direction of the main combustion channel or the pilot combustion channel and having a plate face along the discharging direction of the fuel gas of the plurality of first supply openings or second supply openings distributed along the peripheral direction.
That is to say, the mixing promoting member can be provided as a ring-like member disposed continuously or intermittently across the plurality of first or second supply openings arranged in the peripheral direction of the main combustion channel or the pilot combustion channel. Namely, by causing the fuel gas discharged from the plurality of supply openings arranged in the peripheral direction to collide against the plate surface of this ring-like mixing promoting member, it is possible to diffuse the fuel gas at least in the peripheral direction of the combustion channel.
Further, if the distance between the mixing promoting member and the respective supply openings is too small, this will increase discharging resistance of the fuel gas. Conversely, if the distance is too large, the diffusion of the fuel gas will not be able to take place effectively. Therefore, this distance will be set appropriately, taking into consideration the discharging resistance and the diffusion condition.
Further, in the case of the combination with the fluid distributor as the gas supplying means of the present invention, this mixing promoting member is provided for the first supply openings of the main combustion channel to be utilized for diffusion of the fuel in the main combustion channel. And, by providing the mixing promoting member in the main combustion channel, it is not needed to provide a great number of first supply openings of a small diameter. Instead, it is possible to enlarge the aperture diameter of the first supply opening. Therefore, no significant pressure loss occurs in association with the supply of the fuel, and the mixing degree between the fuel gas and the air may be enhanced by utilizing the air flow. Further, with the reduction of the pressure loss at the first supply openings, the fuel gas discharged from the second supply opening into the pilot combustion channel may be effectively received in the receiving opening communicated with the first supply openings with the reduced pressure loss. In this manner, the mechanism can be realized with a relatively simple construction.
Further, the burner apparatus of the present invention, in addition to the burner apparatus construction described above, is characterized in further that there is provided a second shielding member for adjusting an inflow amount of the oxygen-containing gas, for the second gas supply area extending from the upstream side of the second supply opening in the flow direction of the oxygen-containing gas via the second supply opening of the pilot combustion channel to the receiving opening.
That is to say, by providing the second shielding member on the upstream side of the second supply opening of the second channel as proposed by this construction, it becomes possible to restrict inflow of the air into the second gas supply area from the upstream side of the pilot combustion channel, thereby to appropriately adjust the inflow amount of the air into the second gas supply area. As a result, in the second gas supply area, the ratio of the fuel gas reaching and entering the second supply opening may be adjusted appropriately, so that the distribution ratio of the fuel gas for the main combustion channel may be adjusted to suit the operation condition of the burner apparatus.
Further, as this second shielding member restricts the air entering the second gas supply area from the upstream side, by enlarging the diameter of the second supply opening, the discharging speed of the fuel gas may be reduced for reducing the pressure loss of the fuel gas at the second supply opening.
Further, the burner apparatus of the present invention, in addition to the burner apparatus construction described above, is characterized in further that the second shielding member comprises a member disposed across at least a portion of the second gas supply area upstream in the flow direction of the oxygen-containing gas.
That is, as the second shielding member, it is possible to employ a e.g. flat-plate-like or curved-plate-like member which is disposed across at least a portion of the second gas supply area upstream in the air flow direction and which has a plate surface extending, in e.g. the second channel upstream in the air from of the second supply opening, from a wall portion of the gas channel to a wall portion of the main combustion channel; in a direction normal to or inclined relative to the air flow direction.
In this case too of providing such plate-like member described above, it is possible to restrict inflow of the air from the upstream side of the air flow direction in the pilot combustion channel, for the second gas supply area where the fuel gas is supplied in the pilot combustion channel, thereby to appropriately adjust the inflow amount of air into this second gas supply area, so that the distribution ratio of the fuel gas between the main combustion channel and the pilot combustion channel may be adjusted to suit the operation condition of the burner apparatus.
Further, the burner apparatus of the present invention, in addition to the burner apparatus construction described above, is characterized in further that the second shielding member comprises a tubular member which surrounds a portion of the second gas supply area.
That is to say, the second shielding member may be provided for example as a cylindrical or angular tubular member which extends from the outer periphery of the second supply opening toward the main combustion channel to surround a portion of the second gas supply area.
Further, in the second gas supply area surrounded by such tubular member, the inflow of the air from the upstream side may be restricted reliably and also the discharging direction of the fuel gas may be adjusted with high precision. Also, at the terminal end of the tubular member of the pilot combustion channel there is formed a slit exposed to the air flow of the pilot combustion channel in the second gas supply area. Accordingly, by appropriately setting the width of this slit through adjustment of the height of this tubular member in the axial direction interconnecting the first and second supply openings, the influence of the air flowing into the slit on the flow of the fuel gas may be precisely adjusted to be advantageous and the distribution ratio of the fuel gas between the main combustion channel and the pilot combustion channel may be adjusted to further suit the operation condition of the burner apparatus.
Further, the burner apparatus of the present invention, in addition to the burner apparatus construction described above, is characterized in further that the second shielding member defines an opening for adjusting the inflow condition of the oxygen-containing gas to the second gas supply area.
Namely, by defining at least one circular, slit-like or polygonal opening in the plate-like member as the second shielding member as proposed by this construction, the inflow amount or distribution of the inflow air as the inflow condition of the air into the second gas supply area may be adjusted.
That is to say, the air will flow via the opening through the plate-like member and this through air will flow into the second gas supply area. Hence, by appropriately forming the opening, it is possible to adjust the ratio of the fuel gas passing the second gas supply area and flowing through the receiving opening and the first supply openings into the main combustion channel to suit the operation condition of the burner apparatus.
Further, the burner apparatus of the present invention is characterized in further that discharging resistance of the fuel gas from each said first supply opening due to passage of the oxygen-containing gas is set so as to increase as being distant from the pilot combustion channel.
That is, according to this construction, the main combustion channel includes the plurality of first supply openings for the fuel gas diffused in the direction away from the pilot combustion channel, and discharging resistance of the fuel gas from each said first supply opening due to passage of the oxygen-containing gas is set so as to increase as being distant from the pilot combustion channel. With this, when the supplying pressure of the fuel gas is higher at the time of the rated combustion load, at all of the first supply openings, the fuel gas is supplied to the main combustion channel, overcoming the discharging resistance. Conversely, when the supplying pressure of the fuel gas is low at the time of low combustion load, at those first supply openings of the main combustion channel which opening are disposed away from the pilot combustion channel and provides higher discharging resistance, the discharging of the fuel gas is inhibited by the discharging resistance, so that the fuel gas is discharged to the main combustion channel only from those first supply openings disposed dose to the pilot combustion channel.
Therefore, at the time of rated combustion load, the fuel gas may be supplied entirely in the width direction of the main combustion channel (the direction distant from the pilot combustion channel) to provide the rated combustion load operation with high combustion load. Conversely, in the case of the low combustion load operation, the fuel gas may be supplied more to the portion of the main combustion channel close to the pilot combustion channel than the case of the rated combustion load. Further, in combination with the fluid distributor as the gas supplying means of the present invention, the fuel gas for the main combustion may be ignited and combusted in the pilot combustion under advantageous conditions. Hence, high efficiency is obtained over the wide combustion load range.
Further, the burner apparatus of the present invention, in addition to the burner apparatus construction described above, is characterized in further that the setting of the discharging resistance of the fuel gas is done such that a discharging angle for the fuel gas at each said first supply opening toward the upstream side in the flow direction of the oxygen-containing gas in the main combustion channel is decreased as being distant from the pilot combustion channel.
That is, according to this construction, the discharging angle for the fuel gas at each first supply opening toward the upstream side in the flow direction of the air in the main combustion channel is decreased continuously or stepwise as being distant the pilot combustion channel. With this, those first supply openings disposed away from the pilot combustion channel rather than the first supply openings disposed adjacent the pilot combustion channel will discharge the fuel gas against the flow of the air, thus the discharge gas will experience greater discharging resistance from the air flow. Hence, as the burner apparatus having this construction is capable of supplying the fuel gas to the portion adjacent the pilot combustion channel more at the time of low combustion load than at the time of the rated combustion load, so that the fuel gas for the main combustion may be ignited and combusted in the pilot combustion under the advantageous condition.
Further, the burner apparatus of the present invention, in addition to the burner apparatus construction described above, is characterized in further that the setting of the discharging resistance of the fuel gas is done such that the discharging direction of the fuel gas from the plurality of first supply openings is set to be more upstream than the direction normal to the flow direction of the oxygen-containing gas in the main combustion channel and also that the opening area of each said first supply opening is increased as being distant the pilot combustion channel.
That is to say, according to the present construction, by setting the discharging direction of the fuel gas from the plurality of first supply openings to be more upstream than the direction normal to the flow direction of the air in the main combustion channel, at each first supply opening, the fuel gas will experience discharging resistance in the flow direction of the air, and the greater the opening area of the first supply opening, the greater this discharging resistance of the fuel gas.
Then, by adapting the opening area of the first supply openings to continuously or stepwise increase as being distant the pilot combustion channel, discharging resistance for the fuel gas may be set greater for those first supply openings disposed away from the pilot combustion channel than the first supply openings disclosed closer to the pilot combustion channel. Therefore, with the burner apparatus having this construction, more of the fuel gas may be supplied to the portion dose to the pilot combustion at the time of low combustion load than at the time of the rated combustion load. Hence, the fuel gas for the main combustion may be ignited and combusted under the advantageous condition in the pilot combustion.
Further, the burner apparatus of the present invention is characterized in further that the first supply openings are configured to supply the fuel gas into the first channel along the direction of the main combustion channel distant from the pilot combustion channel; and a first shielding member is provided for preventing inflow of the air from the upstream side along the flow direction of the air in the first channel, for a first gas supply area formed by the fuel gas supplied from the first gas supply openings inside the main combustion channel.
That is, by providing the burner apparatus of the invention with the first shielding member for preventing inflow of the air from the upstream side in the air flow direction of the main combustion channel, i.e., along the axial direction of the inner tube and outer tube, for the gas supply area where the fuel gas is supplied in the main combustion channel, the fuel gas supplied along the direction away from the inner tube and the outer tube will experience of less influence form the air flow, so that the gas will be readily diffused toward the outer side of the main combustion channel relative to the pilot combustion channel. For this reason, the mixing between the fuel gas and the air inside the main combustion channel will take place uniformly, thereby to achieve low NOx generation in the main combustion.
If the fuel gas can be readily diffused to the outer side of the main combustion channel, the discharging speed of the fuel gas at the first supply openings may be reduced. Then, the supply pressure of the fuel gas may be reduced, for example. As a result, the pressure loss in the gas supplying means may be reduced and the such devices as the gas supplying means may be formed compact.
And, in combination with the fluid distributor as the gas supplying means in the present invention, in the distributing means, in supplying the fuel gas through the route from the second supply opening, the pilot combustion channel, the receiving opening, the first supply opening to the main combustion channel, as the first shielding member is provided as above for reducing the pressure loss at the first supply opening, the fuel gas discharged from the second supply opening into the pilot combustion channel may be received efficiently into the receiving opening communicated with the first supply opening with the reduced pressure loss. Thus, with such very simple construction of the gas supplying means, the combustion condition of the main combustion in the main combustion channel and the combustion condition in the pilot combustion in the pilot combustion channel may be set appropriately.
Moreover, if the first shielding member assures the diffusion of the fuel gas into the main combustion channel, the equivalent ratio of the mixture of the air and the fuel gas will be rendered constant at any position in the main combustion channel. As a result, such inconvenience as occurrence of local high-temperature combustion can be avoided, so that the combustion can take place with reduced NOx generation.
Further, the burner apparatus of the present invention, in addition to the burner apparatus construction described above, is characterized in further that a ratio (c/e) between a distance (c) between the opening center of the first supply opening and the first shielding member defined along the air flow direction of the main combustion channel and an opening width (e) of the first supply opening defined in said direction is set to be greater than or equal to 0.5 and smaller than or equal to 1.5.
That is to say, the distance between the first supply opening and the shielding member is specified within a fixed range. Namely, the setting of the ratio (c/e) to 0.5 means that the fuel gas first supply opening is disposed adjacent the shielding member. On the other hand, the setting of the ratio (c/e) to 1.5 means that the distance between the first shielding member and the edge of the first supply opening is equal to the opening width of the fuel supply opening in the axial direction of the pilot combustion channel, in other words, in the axial direction of the inner tube and the outer tube.
By setting the distance between the first supply opening and the shielding member as described above, it is possible to minimize the influence of the air on the fuel gas supplied from the first supply opening into the main combustion channel. Accordingly, the uniformity of the fuel gas to the main combustion channel will be further assured and further reduction in NOx generation in the main combustion can be obtained.
Further, the burner apparatus of the present invention, in addition to the burner apparatus construction described above, is characterized in further that the first shielding member comprises a member which extends in the direction where the main combustion channel extends away from the pilot combustion channel, one first end of the first shielding member on the side adjacent the first supply opening has a width (a) along the peripheral direction of the main combustion channel, the other second end has a width (b) along the peripheral direction, the first supply opening has a width (d) along the peripheral direction; and a ratio (a/d) between said width (a) and said width (d) is greater than or equal to 1 and smaller than or equal to 3, and a ratio (b/d) between said width (b) and said width (d) is greater than or equal to 0 and smaller than or equal to 2.
That is to say, the first shielding member extends, in the main combustion channel, in the direction away from the pilot combustion channel, i.e. in the radial direction of the inner tube and the outer tube and this member has the first and second ends as its opposed ends in the extending direction. And, this construction defines the relationships between the widths of these opposed ends and the opening width of the first supply opening.
Namely, of the two ends of the first shielding member, the one end on the side adjacent the first supply opening is provided as the first end, and the other end apart from the first supply opening is provided as the second end, and the width of the first end in the peripheral direction of the main combustion channel is specified to be one to three times greater than the opening width of the first supply opening in the peripheral direction. That is to say, by setting the width of the first end greater than the width of the first supply opening, direct collision of the air against the fuel gas discharged from the first supply opening to the main combustion channel is avoided. With this, of the velocity of the discharged fuel gas, its radial velocity component can be maintained well in particular, whereby the uniform mixing effect of the fuel gas in the radial direction is improved.
On the other hand, the width of the second end along the peripheral direction is set to be greater than or equal to 0 or smaller than or equal to 2 times greater than the opening width of the first supply opening in the same direction. The fuel gas discharged from the first supply opening into the main combustion channel will flow outward in the radial direction with more or less diffusion. However, due to the discharging speed of the fuel gas or various conditions such as the radial size of the main combustion channel, there will occur a difference in the diffusion conditions in the fuel gas which has reached the vicinity of the second end. Namely, by varying the amount of the air to collide against the fuel gas depending on the degree of diffusion, the equivalent ratio of the fuel-air mixture will be rendered constant through the entire main combustion channel.
Needless to say, the width of the second end may be zero also. That is, if it is desired to cause a large amount of air to collide against the fuel gas so as to increase the stirring effect, the width of the second end will be set as zero. However, in case the diffusion of the fuel gas has developed already in the vicinity of the second end, if the air flow is caused to collide directly thereto, it will be difficult to diffuse the fuel gas to the outermost side of the main combustion channel. In such case, the width of the second end will be set as e.g. about 2 times greater than the width of the first supply opening.
With this construction, it is possible to increase/decrease the degree of diffusion of the fuel gas in the radial direction of the main combustion channel. Therefore, the equivalent ratio of the fuel-air mixture in the main combustion channel may be made uniform and low NOx generation can be realized while providing the gas supplying means as means with reduced pressure loss.
Further, the burner apparatus of the present invention, in addition to the burner apparatus construction described above is characterized in further that a hollow tubular fuel supplying member having a porous wall portion is attached to the first supply opening.
That is to say, as proposed by the present construction, if the porous fuel supplying member is attached to the first supply opening for the fuel gas, the fuel gas will be gradually discharged through the pores formed in the wall portion of the fuel supplying member when the fuel gas moves in the radial direction of the main combustion channel, in other words, in the direction of the cross section of the channel of the main combustion channel. Therefore, the fuel gas may be diffused uniformly over the entire main combustion channel.
In this, it is desired, however, that the porous material used in this construction should have coarse pores as they are needed for preventing pressure loss in fuel supply. That is, the fuel supplying member used in this construction should be such that it can restrain easy diffusion of the fuel gas when the fuel gas flows outwards in the radial direction. For instance, in case this fuel supplying member is disposed in the flow of the air, the member should have such pores as allow easy entry of this air flow into the interior of the fuel supplying member.
If such fuel supplying member is provided and also the first shielding member is provided on the upstream of this fuel supplying member, the fuel gas diffusion restraining effects of these two members will be combined to reliably allow the fuel gas to be diffused to the outer side of the main combustion channel.
Further, the burner apparatus of the present invention, in addition to the burner apparatus construction described above, is characterized in further that said fluid distributor comprises a distributing member which is provided in the main combustion channel and defines the first supply opening in its outer surface, and which forms therein an air inlet duct (an example of an oxygen-containing gas inlet duct) for guiding the air supplied from the supply line and the air supplying means to the pilot combustion channel, and said distributing means includes, in said distributing member, a second supply opening for discharging the fuel gas into the air inlet duct in a direction intersecting the flow direction of the air inside the air inlet duct, a communication line for receiving the fuel gas discharged from the second supply opening and guiding it to the first supply opening, and a receiving opening for the communication line disposed at a position opposing to the second supply opening with a predetermined distance relative thereto in the discharging direction, with the receiving opening being open to the second supply opening.
That is to say, the distributing member is provided in the main combustion channel and the wall portion of the air inlet duct formed inside this distributing member for introducing the air into the pilot combustion channel defines the second supply opening for discharging the fuel gas into the air inlet duct and the wall portion of the air inlet duct formed inside the distributing member defines the receiving opening opposing to the second supply opening via the air inlet duct, to which opening the discharge of the fuel gas is directed. And, this receiving opening is connected via the communication line with the first supply opening defined in the outer surface of the distributing member.
That is, the fuel gas supplied to the supply line inside the distributing member is discharged from the second supply opening toward the receiving opening of the air inlet duct.
And, in the gas supply area where the discharged fuel gas is present in the air inlet duct inside the distributing member, a portion of the fuel gas transversing the air inlet duct is carried way by the air current of the air inlet duct to flow to the pilot combustion channel, while the rest of the gas flows through the air current of the air inlet duct to reach the first supply opening via the receiving opening to be supplied to the main combustion channel eventually.
More particularly, of the fuel gas discharged from the second supply opening into the air inlet duct, the fuel gas portion introduced into the communication line via the receiving opening will be guided to the first supply opening to be supplied to the main combustion channel whereas, the other fuel gas portion not introduced into the receiving opening will be supplied via the air inlet duct to the pilot combustion channel. And, the greater the amount and the greater the speed of the supply of the fuel gas discharged from the second supply opening, the higher the ratio of the portion of the discharged fuel gas introduced into the receiving opening. As a result, the greater the supply amount of the fuel gas, the higher the distribution ratio of the fuel gas to the side of the first supply opening, i.e. to the side of the main combustion channel. Conversely, the smaller the amount of the supply of the fuel gas, the lower the distribution ratio of the fuel gas to the side of the main combustion channel.
Therefore, in the burner apparatus, the distributing means of the fluid distributor may be realized with a simple construction.
Further, the burner apparatus of the present invention, in addition to the burner apparatus construction described above, is characterized in further that the distributing member preferably comprises a plate-like member disposed within the main combustion channel with a plate face thereof being oriented along the flow direction of the oxygen-containing gas in the main combustion channel.
When the distributing member is provided within the main combustion channel as described above, this sometimes results in disturbance in the air flow inside the main combustion channel. However, by constructing this distributing member as a plate-like member having a plate face aligned in the air flow direction, such disturbance of the air in the main combustion channel can be minimized.
For accomplishing the above-noted object, a burner apparatus according to the present invention, includes a common channel formed at one end of the inner tube and the outer tube for supplying the oxygen-containing gas to the main combustion channel and the pilot combustion channel, a common supply opening for discharging the fuel gas of the gas channel in said common channel from the upstream side in the flow direction of the oxygen-containing gas of the pilot combustion channel to the upstream side in the flow direction of the oxygen-containing gas of the main combustion channel, and a common shielding member for adjusting the inflow amount of the oxygen-containing gas, for a common gas supply area which extends in a discharging direction of the fuel gas from the upstream side in the air flow direction of the common supply opening and from this common supply opening to the common channel.
Further, the burner apparatus of the present invention, in addition to the burner apparatus construction described above, is characterized in further that said first channel is used as the main combustion channel and said second channel is used as the pilot combustion channel.
That is to say, with the burner apparatus of the present invention, as in this construction, for example, the common channel is provided as a channel formed on the upstream side of the air flow of the inner tube and inside the outer tube, and the common supply opening is provided for causing the gas supplying means to discharge the fuel gas of the gas channel in the above-described direction to the common channel.
Namely, the fuel gas supplied to the gas channel will be discharged from the common supply opening provided in the common channel disposed on the upstream side of the pilot combustion channel toward the common channel disposed on the upstream side of the main combustion channel.
And, in the gas supply area where the discharged fuel gas is present in the common channel, a portion of the fuel gas transversing the common channel is carried way by the air current of the air introduced in the pilot combustion channel to flow to the pilot combustion channel, while the rest of the gas flows through the air current introduced in the pilot combustion channel to reach the air introduced in the main combustion channel to be supplied to the main combustion channel eventually.
Therefore, the greater the supply amount of the fuel gas to the gas channel and the greater the discharging speed of the fuel gas from the common supply opening to the common channel, the higher the ratio of the fuel gas reaching the common channel on the upstream side of the main combustion channel and flowing into the main combustion channel. As a result, by increasing the supply amount of the fuel gas, it is possible to increase the distribution ratio of the fuel gas to the main combustion channel. Conversely, by decreasing the supply amount of the fuel gas, it is possible to decrease the distribution ratio of the fuel gas to the main combustion channel.
Further, with the burner apparatus having this construction, the common shielding member is provided on the upstream side of the common supply opening of the common channel, so that it is possible to restrain the inflow of the air from the upstream side at least to the common gas supply area where the fuel gas discharged in the common channel on the upstream of the pilot combustion channel is present, thereby to appropriately adjust the inflow amount of the air to the common gas supply area. Hence, in the common gas supply area, the ratio of the fuel gas reaching the upstream of the main combustion channel and introduced therein may be adjusted appropriately, so that the distribution ratio of the fuel gas to the main combustion channel may be adjusted to suit the operation condition of the burner apparatus.
Further, as this common shielding member restrains the inflow of the air from the upstream side of the air from into the gas area, it is possible to increase the diameter of the common supply opening for reducing the discharging speed of the fuel gas, eventually reducing the pressure loss of the fuel gas at the common supply opening.
Therefore, it is not necessary to adjust the supply amount of the fuel gas to the pilot combustion channel and the supply amount of the fuel gas to the main combustion channel independently of each other. Rather, the distributing means may be constructed such that only with adjustment of the total supply amount of the fuel gas to the gas channel, the distribution ratio of the fuel gas to the main combustion channel and to the pilot combustion channel may be readily adjusted in accordance with e.g. combustion load variation. Moreover, the supply amount of the fuel gas to the pilot combustion channel may be increased in association with decrease in the total supply amount of the fuel gas at the time of low combustion load, thereby to assure stable pilot combustion. At the same time, the supply amount of the fuel gas to the main combustion channel may be increased in association with increase in the total supply amount of the fuel gas at the time of the rated combustion load, so that the fuel gas may be distributed uniformly to the main combustion channel and the pilot combustion channel to realize low NOx generation combustion with lean fuel-air mixture. Accordingly, there is achieved a burner apparatus which has a simple construction, but which achieves higher efficiency over wide combustion load range.
Further, in the burner apparatus of the present invention, of the outer first channel and the inner second channel, either combustion channel may be used as the main combustion channel. However, if the outer first channel is used as the main combustion channel and the inner second channel is used as the pilot combustion channel, at the time of low combustion load when the distribution ratio of the fuel gas for the pilot combustion channel is increased, more fuel gas will be introduced to the inner pilot combustion channel for assuring stable pilot combustion in the pilot combustion channel.
Also, the above-described burner apparatus of the present invention which achieves low NOx generation and high efficiency over a wide combustion load range can be used by itself as a burner apparatus for an incinerator for example. However, this apparatus is particularly useful as a burner apparatus for a gas turbine engine. Such gas turbine engine can operate over a wide operational load range while maintaining low NOx reduction and high efficiency.
Further, with a co-generation system including the gas turbine engine having the fluid distributor and the burner apparatus of the invention and a heat recovery device for recovering heat from exhaust gas, since the exhaust gas exhausted from the gas turbine engine has low NOx content, such device as a denitration device can be formed small or eliminated at all, so that cost reduction and size reduction of the system can be achieved.